Shut-off device for the filling device of a pressure tank

ABSTRACT

The invention relates to a shut-off apparatus for the charging device of a pressure vessel, especially for the storage of cryogenic liquefied gases, having a shut-off valve with a valve housing and a valve body stressed by a closure spring which, in order to charge the pressure vessel, can be brought into the open position against the force of the closure spring, having an apparatus for locking the valve body in the open position of the valve and having a release apparatus subjected to the action of the vessel pressure, which causes the apparatus to release the lock if a predetermined threshold vessel pressure is exceeded. According to the invention, the vessel threshold pressure at which closure of the charging device takes place can be preset with considerably more accuracy in that the release apparatus possesses a cylinder ( 1 ), a piston ( 2 ) and a piston rod ( 3 ), in that a medium-permeable annular gap is provided between piston ( 2 ) and cylinder ( 1 ), in that the piston rod ( 3 ) acts on the apparatus to release the lock, in that the cylinder ( 1 ) possesses an overflow valve ( 4, 12 ) on one side of the piston ( 2 ) which opens when the threshold vessel pressure is reached, in that, when the overflow valve ( 4, 12 ) is open, the cylinder ( 1 ) is in flow connection with the pressure vessel on one side of the piston ( 2 ) and is in flow connection with a reference pressure volume, preferably the ambient atmosphere, on the other side of the piston.

BACKGROUND OF THE INVENTION

The invention relates to a shut-off apparatus for the charging device ofa pressure vessel, especially for the storage of cryogenic liquefiedgases, having a shut-off valve with a valve housing and a valve bodystressed by a closure spring which, in order to charge the pressurevessel, can be brought into the open position against the force of theclosure spring, having an apparatus for locking the valve body in theopen position of the valve and having a release apparatus subjected tothe action of the vessel pressure, which causes the apparatus to releasethe lock if a predetermined threshold vessel pressure is exceeded.

An essential aspect of the design of shut-off apparatuses for thecharging device of a pressure vessel is the reliable avoidance of excesspressures when charging the pressure vessels.

The shut-off apparatuses must first offer a maximum level of safety andsecondly exclude as effectively as possible any manipulation orswitching-off of the shut-off apparatuses. In particular, an independentcontrol of the shut-off apparatus which is as isolated as possible fromexternal influences must be guaranteed.

DE-OS 21 56 068 has disclosed a shut-off apparatus controlled by anindependent medium for avoiding excess pressures in a gas or fluid linewith a shut-off valve, in which the valve body is equipped with aresilient means in the form of a closure spring to generate a force inthe closed position, an apparatus for locking being provided in the formof a locking lever and an assigned projection on the valve stem, thislocking apparatus permitting the locking of the shut-off valve in theopen position against the force acting towards the closed position, andthis locking apparatus comprising release apparatuses for releasing thelocking apparatus in the event that the pressure rises above or fallsbelow a predetermined maximum or minimum pressure.

DE 196 50 560 A1 has likewise disclosed a shut-off apparatus for thecharging device of a pressure vessel, in which the release apparatuspossesses a bellows subjected to the vessel pressure with a switch rodattached thereto which pivots the locking apparatus of the valve body,designed as a closure lever, out of the locking position into therelease position if vessel pressures exceed or fall below vesselthreshold pressures.

In the known shut-off apparatuses for the charging device of a pressurevessel it is a problem, depending on the surroundings and the existingsafety regulations, that the cryogenic gas is blown off during releaseand also after release. In some circumstances, the place of escape hasto be moved by the costly piping of the gas into low hazard potentialareas. It is also advantageous if the control line between the pressurevessel and the release apparatus possesses a narrow cross section —as iscustomary in signal lines.

SUMMARY OF THE INVENTION

Starting from this state of the art, therefore, the object of theinvention is to provide a release apparatus for a shut-off apparatuswhich permits the release of the shut-off apparatus with little or noblow-off of the cryogenic gases conveyed.

The object derived and described above is achieved, according to theinvention in that the release apparatus possesses a cylinder, a pistonand a piston rod, in that a medium-permeable annular gap is providedbetween piston and cylinder, in that the piston rod acts on theapparatus to release the lock, in that the cylinder possesses anoverflow valve on one side of the piston which opens when the thresholdvessel pressure is reached, in that, when the overflow valve is open,the cylinder is in flow connection with the pressure vessel on one sideof the piston and is in flow connection with a reference pressurevolume, preferably the ambient atmosphere, on the other side of thepiston.

With the improved release apparatus of the shut-off apparatus accordingto the invention, the release of the locking apparatus as a preciselyreproducible step function is guaranteed in that the switching forcesare abruptly boosted via a pneumatic booster at the start of theoverflow valve opening operation, which can be precisely predetermined.In the shut-off apparatus according to the invention, this abrupt boostis guaranteed by simple pneumatic means and not by precision engineeringwith the disadvantages of costly production and adjustment. As soon asthe overflow valve opens, a differential pressure arises across theannular gap between piston and cylinder and, by acting on the pistonsurface, guarantees a pneumatic force boost to release the shut-offapparatus.

As a result of the fact that, according to a first alternativeembodiment of the shut-off apparatus according to the invention, anunobstructed control line opens into the cylinder on one side of thepiston to create the flow connection to the pressure vessel and that thecylinder is connected to the overflow valve on the other side of thepiston, the vessel pressure prevails in the entire cylinder when theoverflow valve is shut. If the vessel pressure exceeds the vesselthreshold pressure, the overflow valve opens, as a result of which,because of the relatively narrow annular gap, a lower pressure arises onthe side of the piston opposite the control line than on the other sideof the piston, which in turn results in the piston being subjected to ahigh force towards the side of the piston remote from the unobstructedcontrol line to release the shut-off apparatus.

As an alternative to the embodiment of the shut-off apparatus accordingto the invention just described, a control line opens into the cylinderon one side of the piston via the overflow valve to create the flowconnection to the pressure vessel and the cylinder is in unobstructedflow connection with the reference pressure volume on the other side ofthe piston. In this alternative version, the cylinder is under thepressure of the reference pressure volume when the overflow valve isshut. As soon as the overflow valve opens, in this alternative version,the pressure on the side of the piston facing the control line risesrapidly because of the narrow annular gap, so that the pressuredifference between the two sides of the piston pneumatically boosts theopening of the overflow valve.

The effect is that, in both alternative versions, the embodimentaccording to the invention ensures that the piston rod of the releaseapparatus is abruptly accelerated at the moment when the overflow valvebegins to open and thus acts on the apparatus by way of a single-stepfunction to release the locking.

In order to bring about a defined initial state and to restore therelease apparatus automatically when necessary, it is advantageous that,according to another embodiment of the invention, the piston rod issubjected to force via a spring towards the side of the piston facingthe control line.

The second alternative embodiment of the release apparatus described isadvantageously further developed in that the end of the piston rodfacing the control line bears the sealing element of the over flowvalve. This guarantees that the piston rod of the release apparatus,which is subjected to force, forms the overflow valve together with thesealing element and the valve seat arranged at one end of the cylinder.As a result, the number of components is reduced by comparison with anembodiment with a separate overflow valve.

If it is desired, in the case of the second alternative embodiment, thatthe release apparatus should not be restored automatically when thevessel pressure drops below the vessel threshold pressure, this can beguaranteed in that the cylinder and the piston on the side remote fromthe control line interrupt the flow connection to the reference pressurevolume in the end position of the piston movement. As a result of theinterruption of the flow connection to the reference pressure volume,the pressure in the cylinder is statically held at the vessel pressure,since the gas cannot flow out via the flow connection to the referencepressure volume. This static pressure difference then ensures that thepiston cannot be restored automatically.

For controlled restoration, the shut-off apparatus according to theinvention is further developed in that the cylinder is in flowconnection with the reference pressure volume via a valve on the sidefacing the control line. Via such a valve, which may for example bemanually actuated, it is possible to reduce the pressure on the side ofthe piston facing the control line to such an extent that a resetting ofthe piston and hence of the release apparatus becomes possible.

The two alternative embodiments of the release apparatus described areadvantageous in that the control line does not require any large crosssections and in that little or no blow-off of the gases or media takeplace at the release apparatus. In particular, in the embodiment of thesecond alternative version, in which the flow connections to thereference pressure volume are interrupted by interaction of cylinder andpiston, only a small quantity of gas or medium enters the referencepressure volume meaning, in particular, the environment.

There are many possible ways of embodying and developing the shut-offapparatus according to the invention for the charging device of apressure vessel. In this connection, reference is made by ways ofexample first to the patent claims dependent on Patent claim 1 andsecondly to the description of examples of embodiment of the shut-offapparatus according to the invention for the charging device of apressure vessel in conjunction with the drawing. In the drawing:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a simplified sectional view of the essential components ofa first example of embodiment of a shut-off apparatus according to theinvention, and

FIG. 2 shows a simplified sectional view of the essential components ofa second example of embodiment of a shut-off apparatus according to theinvention.

DETAILED DESCRIPTION OF THE INVENTION

The illustration in FIGS. 1 and 2 does not give a complete view of theshut-off apparatus according to the invention for the charging device ofa pressure vessel but shows only those components of a release apparatussubjected to the vessel pressure that causes the apparatus to releasethe locking when a predetermined vessel threshold pressure is exceededthat are essential to the invention.

The embodiment shown in FIG. 1, which is essential to the invention, ofthe release apparatus of the first example of embodiment possesses acylinder 1, a piston 2 and a piston rod 3, a medium-permeable annulargap being provided between piston 2 and cylinder 1. The piston rod 3acts on the apparatus (not shown) for releasing the locking. Thecylinder 1 possesses an overflow valve 4 on one side of the piston 2which opens when the vessel threshold pressure is reached. With theoverflow valve 4 open, the cylinder 1 is in flow connection via aconnector 5 on one side of the piston 2 with the pressure vessel (notshown) and is in flow connection via an outlet 6 with a referencepressure volume, in this case the ambient atmosphere, on the other sideof the piston 2. To reset the piston 2, a spring 7 is provided betweenthe cylinder 1 and the piston 2. To set the vessel threshold pressure,the sealing piece 8 of the overflow valve 4 is subjected to a forcetowards the valve seat 10 by a spring 9.

Located in the cylinder 1 is the piston 2 with a two-ended (continuous)piston rod 3. The piston 2 is not sealed off from the cylinder 1, inother words does not contact the cylinder inside wall, so that anannular slit exists between piston 2 and cylinder inside wall. Theinterior of the cylinder is connected to the pressure space, for examplea cold gasifier. The two ends of the piston rod and all internals aresealed off in a gas-tight manner from the outside. The piston 2 ispressed downward by the spring 7 against a stop. The pressure prevailingin the cylinder 1 acts uniformly on both sides of the disc-shaped piston2. The piston rod 3 also exerts no pressure-dependent forces. On theside of the piston 2 remote from an unobstructed control line 11 tocreate the flow connection to the pressure vessel (not shown), theinterior of the cylinder is connected to a spring-loaded overflow valve4. This overflow valve 4 opens when the shut-off apparatus according tothe invention reaches the desired, set vessel threshold pressure. Whenthe overflow valve 4 opens, a generally gaseous medium is drawn from thecorresponding part of the cylinder. A differential pressure arisesacross the annular gap between the cylinder 1 and the piston 2,resulting in a compressive force which leads to spontaneous raising ofthe piston 2. The piston rod 3 then actuates, in a manner known per se(of for example DE 196 50 560 A1) an apparatus for locking the valvebody, so that a shut-off valve is closed.

As soon as the pressure in the cylinder 1 falls to the point where theoverflow valve 4 closes again, a compensated pressure exists throughoutthe cylinder 1 after a short interval. The spring 7 than pushes thepiston 2 back into the starting position, so that the release apparatusagain allows the locking of the shut-off valve (not shown) in the openposition.

By miniaturization of the overflow valve 4, the quantity of gas blownout during each release operation is kept very low despite high releaseforces.

In the example of embodiment shown in FIG. 2, the components performingthe same functions are given the same reference numbers.

In the example of embodiment shown in FIG. 2, the pressure space of acold gasifier (not shown) is connected via the control line 11 to aspring-loaded overflow valve 12. A sealing element 8 on the piston 2closes the control line 11 in a gas-tight manner. Atmospheric pressuretherefore prevails above the overflow valve 11. The overflow valve 12 isset, via the spring 7, so that the start of opening (stroke) correspondsto the desired switching pressure.

With this opening operation, gas flows past the sealing element 8 andgenerates a compressive force on the large surface of the unsealedpiston 2 which results in the spontaneous lifting movement of the piston2 and hence of the piston rod 3. As a result, the apparatus (not shown)for locking the valve body in the open position of the shut-off valve isactuated. In the upper piston end position in FIG. 2, the piston 2 lieson a sealing ring 13, so that a continuous outflow of gas through thesecondary bore 14 and the outlet 6 is prevented.

If the piston lies on the sealing ring 13 in the piston end position,the container pressure acts without flow, in other words statically, onthe piston 2. No gas losses occur. The release apparatus remains in thisposition on condition that the vessel pressure does not fallsubstantially. In other words, the release apparatus is notautomatically reset. If a laterally affixed sensor valve 15 is nowactuated manually, the cylinder 1 is relieved of pressure on the side ofthe piston 2 facing the control line 11. As a result, the compressiveforce on the piston 2 is reduced to the point where the piston 2 moves,under spring load, into the closed position of the overflow valve 12.The outflow process from the manually actuated sensor valve 15 is thusautomatically ended.

In the example of embodiment shown in FIG. 2, the static pressure isalmost exclusively sufficient for release, which is equivalent to sayingthat, after the release, no undesired outflow of the stored medium takesplace.

What is claimed is:
 1. Shut-off apparatus for the charging device of apressure vessel, especially for the storage of cryogenic liquefiedgases, having a shut-off valve with a valve housing and a valve bodystressed by a closure spring which, in order to charge the pressurevessel, can be brought into the open position against the force of theclosure spring, having a release apparatus subjected to the action ofthe vessel pressure, which causes the apparatus to release a lock if apredetermined threshold vessel pressure is exceeded, characterized inthat the release apparatus possesses a cylinder (1), a piston (2) and apiston rod (3), in that a medium-permeable annular gap is providedbetween piston (2) and cylinder (1), in that the piston rod (3) acts onthe apparatus to release the lock, in that the cylinder (1) possesses anoverflow valve (4, 12) on one side of the piston (2) which opens whenthe threshold vessel pressure is reached, in that, when the overflowvalve (4, 12) is open, the cylinder (1) is in flow connection with thepressure vessel on one side of the piston (2) and is in flow connectionwith a reference pressure volume, preferably the ambient atmosphere, onthe other side of the piston.
 2. Shut-off apparatus according to claim1, characterized in that an unobstructed control line (11) opens in thecylinder (1), on one side of the piston (2), to create the flowconnection to the pressure vessel and in that the cylinder (1) isconnected to the overflow valve (4) on the other side of the piston (2).3. Shut-off apparatus according to claim 1, characterized in that acontrol line (11) opens in the cylinder (1) on one side of the piston(2) via the overflow valve (12) to create the flow connection to thepressure vessel and in that the cylinder (1) is in unobstructed flowconnection with the reference pressure volume on the other side of thepiston (2).
 4. Shut-off apparatus according to claim 3, characterized inthat the piston rod is subjected to force via a spring towards the sideof the piston facing the control line.
 5. Shut-off apparatus accordingto claim 4, characterized in that the end of the piston rod facing thecontrol line bears the sealing element of the overflow valve. 6.Shut-off apparatus according to claim 5, characterized in that thecylinder and the piston interrupt the flow connection to the referencepressure volume on the side remote from the control line in the endposition of the piston movement away from the control line.
 7. Shut-offapparatus according to claim 6, characterized in that the cylinder canbe flow-connected to the reference pressure volume via a valve on theside facing the control line.
 8. Shut-off apparatus according to claim1, characterized in that the piston rod is subjected to force via aspring towards the side of the piston facing the control line. 9.Shut-off apparatus according to claim 3, characterized in that the endof the piston rod facing the control line bears the sealing element ofthe overflow valve.
 10. Shut-off apparatus according to claim 3,characterized in that the cylinder and the piston interrupt the flowconnection to the reference pressure volume on the side remote from thecontrol line in the end position of the piston movement away from thecontrol line.
 11. Shut-off apparatus according to claim 3, characterizedin that the cylinder can be flow-connected to the reference pressurevolume via a valve on the side facing the control line.